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Site description (2001 baseline):
Site location and context
Candaba Swamp is near the towns of Candaba, San Miguel and San Ildefonso, c.50 km north-north-west of Metro Manila, in Pampanga and Bulacan Provinces, central Luzon. It is a complex of freshwater ponds, swamps and marshes with surrounding areas of seasonally flooded grassland, arable land and palm savanna on a vast alluvial flood plain. The entire area is usually flooded in the wet season, but most of it dries out during the dry season (late November to April) and is converted into rice fields and plantations of watermelons. The main area for waterfowl is an impoundment of about 300 ha, with a mixture of open shallow water, small islands, and rafts of floating vegetation, adjacent to the Pampanga River about nine kilometers north of Baliuag. However, this area is now drained earlier in the year than in the past, and it no longer attracts many waterfowl. The isolated Mt Arayat, which rises to 1,023 m and has disturbed lowland forest on its slopes, is adjacent to Candaba Marsh but is not included in the IBA.
Most of the flood plain has been converted to privately owned agricultural and residential land except for the core area of approximately 500 ha. The impoundment is used as a fishpond during the rainy season, and then drained in January or February to be used for agriculture. Candaba Swamp acts as a natural flood retention basin holding wet season overflow from the Maasim, San Miguel, Garlang, Bulu and Penaranda Rivers, and draining into the Pampanga River. The swamp was a traditional waterfowl hunting area in the past, and some hunting of ducks and rails, although now illegal, still occurs. It is also a favourite spot for local and visiting bird watchers and naturalists, and possibly has some potential for nature oriented outdoor recreation and conservation education as there are few other places so close to the metropolitan area of Manila that support as much wildlife.
Candaba Swamp was formerly an extremely important staging and wintering area for ducks, especially in October and November when the swamp regularly supported between 5,000 and 10,000 birds. In 1982, about 100,000 ducks were observed in a single day. No other site in the Philippines has been known to support such large concentrations of Anatidae, but the number of wintering wildfowl has recently declined dramatically. Several threatened waterbirds occurred there in the past, although the populations of some of these have presumably declined or disappeared. However, it still supports the only known regular wintering population of Streaked Reed-warbler in the world.
Some of the restricted-range birds of the Luzon EBA were recorded adjacent to this IBA on Mt Arayat in the late 19th century, including Green Racquet-tail Prioniturus luconensis (threatened), Red-crested Malkoha Phaenicophaeus superciliosus, Rufous Coucal Centropus unirufus, Grey-backed Tailorbird Orthotomus derbianus and White-fronted Tit Parus semilarvatus. This small mountain is reported to retain some forest cover, but there appears to be no recent information on the status of these species there. There has been no mammal survey in Candaba swamp and on Mt Arayat.
Non-bird biodiversity: There has been no mammal survey in Candaba swamp and on Mt Arayat.
Candaba Swamp is near the towns of Candaba, San Miguel and San Ildefonso, c.50 km north-north-west of Metro Manila, in Pampanga and Bulacan Provinces, central Luzon. It is a complex of freshwater ponds, swamps and marshes with surrounding areas of seasonally flooded grassland, arable land and palm savanna on a vast alluvial flood plain. The entire area is usually flooded in the wet season, but most of it dries out during the dry season (late November to April) and is converted into rice fields and plantations of watermelons. The main area for waterfowl is an impoundment of about 300 ha, with a mixture of open shallow water, small islands, and rafts of floating vegetation, adjacent to the Pampanga River about nine kilometers north of Baliuag. However, this area is now drained earlier in the year than in the past, and it no longer attracts many waterfowl. The isolated Mt Arayat, which rises to 1,023 m and has disturbed lowland forest on its slopes, is adjacent to Candaba Marsh but is not included in the IBA.
Most of the flood plain has been converted to privately owned agricultural and residential land except for the core area of approximately 500 ha. The impoundment is used as a fishpond during the rainy season, and then drained in January or February to be used for agriculture. Candaba Swamp acts as a natural flood retention basin holding wet season overflow from the Maasim, San Miguel, Garlang, Bulu and Penaranda Rivers, and draining into the Pampanga River. The swamp was a traditional waterfowl hunting area in the past, and some hunting of ducks and rails, although now illegal, still occurs. It is also a favourite spot for local and visiting bird watchers and naturalists, and possibly has some potential for nature oriented outdoor recreation and conservation education as there are few other places so close to the metropolitan area of Manila that support as much wildlife.
Pressure/threats to key biodiversity
The main threats to Candaba Swamp are the conversion of marshland to agricultural purposes, and changes in agricultural practices. In recent years the local people have started to grow rice instead of watermelons in the surrounding area, which entails draining the marshes in December or January instead of March or April. As a result only a few ducks now winter at Candaba. The effect on other waterbird species is unknown. There is a possibility that water levels may be controlled further so that crops can be grown all year round.
Other threats to the wetlands and their biodiversity include siltation and the introduction of exotic fish species. Hunting of waterbirds for food and recreational purposes is a continuing and persistent problem, although now illegal.
Conservation responses/actions for key biodiversity
A workshop was held by DENR, the Haribon Foundation and the Wild Bird Society of Japan in 1994 to develop an action plan for the conservation of the swamp and its waterbirds with the participation of the local government of Pampanga and community leaders.
This is a potential Ramsar site but not a protected area.
Recommended citation
BirdLife International (2024) Important Bird Area factsheet: Candaba swamp (Philippines). Downloaded from
https://datazone.birdlife.org/site/factsheet/candaba-swamp-iba-philippines on 22/11/2024.
